package cn.itcast.zt.example.concurrent;

import cn.itcast.zt.annotation.ThreadSafe;
import lombok.extern.slf4j.Slf4j;

import java.util.Map;
import java.util.concurrent.*;

/**
 * java并发容器ConcurrentHashMap
 * create by zhangtian on 2018/4/8
 */
@Slf4j
@ThreadSafe
public class ConcurrentHashMapExample {

    // 请求总数
    public static int clientTotal = 5000;

    // 同时并发执行的线程数
    public static int threadTotal = 200;

    private static Map<Integer, Integer> map = new ConcurrentHashMap<>() ;

    public static void main(String[] args) throws Exception {
        ExecutorService executorService = Executors.newCachedThreadPool() ;
        final Semaphore semaphore = new Semaphore(threadTotal) ;
        final CountDownLatch countDownLatch = new CountDownLatch(clientTotal) ;

        for (int i = 0; i < clientTotal; i++) {
            final int count = i ;
            executorService.execute(()->{
                try {
                    semaphore.acquire();
                    update(count);
                    semaphore.release();
                } catch (InterruptedException e) {
                    log.error("exception", e);
                }

                countDownLatch.countDown();
            });
        }

        countDownLatch.await();
        log.info("size:{}", map.size());
        executorService.shutdown();
    }

    private static void update(int i) {
        map.put(i, i);
    }
}
